1、Designation: C996 10Standard Specification forUranium Hexafluoride Enriched to Less Than 5 %235U1This standard is issued under the fixed designation C996; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers nuclear grade uraniumhexafluoride (UF6) that either has been processed through anenrichment plant, or has be
3、en produced by the blending ofHighly Enriched Uranium with other uranium to obtain ura-nium of any235U concentration below 5 % and that is intendedfor fuel fabrication. The objectives of this specification aretwofold: (1) To define the impurity and uranium isotope limitsfor Enriched Commercial Grade
4、 UF6so that, with respect tofuel design and manufacture, it is essentially equivalent toenriched uranium made from natural UF6; and (2) To definelimits for Enriched Reprocessed UF6to be expected if Repro-cessed UF6is to be enriched without dilution with CommercialNatural UF6. For such UF6, special p
5、rovisions, not definedherein, may be needed to ensure fuel performance and toprotect the work force, process equipment, and the environ-ment.1.2 This specification is intended to provide the nuclearindustry with a standard for enriched UF6that is to be used inthe production of sinterable UO2powder f
6、or fuel fabrication.In addition to this specification, the parties concerned mayagree to other appropriate conditions.1.3 The scope of this specification does not comprehen-sively cover all provisions for preventing criticality accidentsor requirements for health and safety or for shipping. Obser-va
7、nce of this specification does not relieve the user of theobligation to conform to all applicable international, federal,state, and local regulations for processing, shipping, or in anyother way using UF6(see, for example, TID-7016, DP-532, andDOE O474.1).1.4 The values stated in SI units are to be
8、regarded as thestandard. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Radiochemical Analysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for En
9、rich-mentC859 Terminology Relating to Nuclear MaterialsC1052 Practice for Bulk Sampling of Liquid UraniumHexafluorideC1703 Practice for Sampling of Gaseous UraniumHexafluorideE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ANSI Standards:3ANSI/AS
10、ME NQA-1 Quality Assurance Requirements forNuclear Facility ApplicationsANSI N14.1 Nuclear MaterialsUranium HexafluoridePackaging for Transport2.3 U.S. Government Documents:Inspection, Weighing, and Sampling of Uranium Hexafluo-ride Cylinders, Procedure for Handling and Analysis ofUranium Hexafluori
11、de, Vol. 1, DOE Report ORO-671-1,latest revision4Nuclear Safety Guide, U.S. NRC Report TID-7016, Rev. 2,1978Clarke, H. K., Handbook of Nuclear Safety, DOE ReportDP-5324Code of Federal Regulations, Title 10, Part 50, (AppendixB)42.4 Other Document:The UF6Manual: Good Handling Practices for Uranium1Th
12、is specification is under the jurisdiction of ASTM Committee C26 onNuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.02 on Fueland Fertile Material Specifications.Current edition approved Oct. 1, 2010. Published October 2010. Originallyapproved in 1983. Last previous edition ap
13、proved in 2004 as C996 04E01. DOI:10.1520/C0996-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available
14、 from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
15、 West Conshohocken, PA 19428-2959, United States.Hexafluoride, United States Enrichment Corporation Re-port USEC-651, latest revision53. Terminology3.1 Definitions of Terms Specific to This StandardTermsshall be defined in accordance with Terminology C859 exceptfor the following:3.1.1 Commercial Nat
16、ural UF6UF6from natural unirra-diated uranium (containing 0.711 6 0.004 g235U per 100 g U).3.1.1.1 DiscussionIt is recognized that some contamina-tion with reprocessed uranium may occur during routineprocessing. This is acceptable provided that the UF6meets therequirements for Commercial Natural UF6
17、as specified inSpecification C787.3.1.2 Reprocessed UF6any UF6made from uranium thathas been exposed in a neutron irradiation facility and subse-quently chemically separated from the fission products andtransuranic isotopes so generated.3.1.3 Highly Enriched Uraniumany form of uraniumhaving a235U co
18、ntent of 20 % or greater3.1.4 Enriched Commercial Grade UF6UF6enrichedfrom Commercial Natural UF6or Derived Enriched UF6thatmeets the specification limits for Enriched Commercial GradeUF6.3.1.5 Enriched Reprocessed UF6UF6enriched from Re-processed UF6, any mixture of Reprocessed UF6and Commer-cial N
19、atural UF6or Derived Enriched UF6, exceeding theapplicable limits of Sections 4 and 5 for Enriched CommercialGrade UF6. The wide range of irradiation levels, cooling times,reprocessing, conversion, and enrichment processes, and fuelcycle choices for combination with unirradiated UF6, togetherwith th
20、e varying acceptance limits of different fuel fabricationfacilities, make it not practical to specify the exact radionuclidecomposition of Enriched Reprocessed UF6.3.1.6 Derived Enriched UF6any UF6obtained from theblending of Highly Enriched Uranium with any other uranium.3.2 For enriched UF6transac
21、tions, “buyer” usually repre-sents the electric power utility company or the fuel fabricator,and “seller” usually represents the isotopic enrichment facility.4. Safety, Health Physics, and Criticality Requirements4.1 The UF6concentration shall not be less than 99.5 g UF6per 100 g of sample in order
22、to limit the potential hydrogencontent for nuclear criticality safety.4.2 The total absolute vapor pressure shall not exceed thevalues given below:380 kPa at 80C (55 psia at 176F), or517 kPa at 93C (75 psia at 200F), or862 kPa at 112C (125 psia at 235F)Additionally, if a measurement is taken over so
23、lid UF6, thevapor pressure shall not exceed the values given below:50 kPa at 20C (7 psia at 68F), or69 kPa at 35C (10 psia at 95F)The purpose of the pressure check is to limit the hydrogenfluoride, air, or other volatile components that might causeoverpressure when heating the shipping container, su
24、ch as toobtain a liquid sample or withdraw the contents.4.3 The total hydrocarbon, chlorocarbon, and partially sub-stituted halohydrocarbon content shall not exceed 0.01 mol %of the UF6. The reason for the exclusion of these materials isto prevent a vigorous reaction with UF6upon heating. It isessen
25、tial that contamination of the UF6containers, such as byvacuum pump oil, be prevented since it is not practical toobtain a sample without heating the UF6. An alternative meansof demonstrating compliance with this requirement, other thanby direct measurement, may be agreed upon between theparties con
26、cerned.4.3.1 Measures should be taken to minimize contaminationby hydrocarbons, chlorocarbons and halohydrocarbons in thereceiving cylinder before filling.4.3.2 Also, it is good practice to minimize contact ofhydrocarbon, chlorocarbon, and partially substituted halohy-drocarbon during UF6 processing
27、.4.3.3 If UF6has been liquefied, either during filling orduring sampling of the final shipping container, compliancecan be assumed. If the UF6has not been liquefied, compliancemust be demonstrated. An alternative means of demonstratingcompliance with this requirement, other than by direct mea-sureme
28、nt, may be agreed upon between the parties concerned.4.4 For Enriched Commercial Grade UF6meeting the re-quirements of Section 5,(1) the gamma activity from fissionproducts is expected to be below the detection limits of themeasurement methodology; and (2) the alpha activity fromneptunium and pluton
29、ium is expected to be below the detectionlimits of commonly used measurement methodology. There-fore unless otherwise agreed upon between the buyer andseller, measurements are not required, except for DerivedEnriched UF6resulting from blending with reprocessed ura-nium.4.5 For Enriched Reprocessed U
30、F6, the gamma radiationfrom fission products shall not exceed 4.4 3 105MeVBq/kgU(4.4 3 105MeV/sec kgU).4.5.1 For Enriched Reprocessed UF6, the alpha activityfrom neptunium and plutonium shall be less than 3300 Bq/kgU(200 000 dpm/kgU).5. Chemical, Physical, and Isotopic Requirements5.1 Both Enriched
31、Commercial Grade UF6and EnrichedReprocessed UF6must meet the specification criteria except asdifferentiated in 4.4, 4.5, 5.4, and 5.5. For certain isotopes,including artificially created radioactive species, two groups oflimits are set. Limits for Enriched Commercial Grade UF6areset so as to have no
32、 special impact on the use of this materialin existing facilities. For Enriched Reprocessed UF6, higherlimits are indicated to correspond with Specification C787, andlower limits may be agreed upon by the buyer and selleraccording to the composition of the feed material presented forenrichment.5.2 T
33、he UF6content shall be reported as gUF6/100 gsample.5.3 The following impurities shall not exceed these values:Element g/gUBoron 4Silicon 2505Available from United States Enrichment Corporation, 6903 Rockledge Drive,Bethesda, MD 20817.C996 102For fully substituted chlorofluorocarbons a maximum limit
34、may be agreed upon between the parties concerned.5.4 Enriched Commercial Grade UF6shall comply with thelimits given in 5.5. For evaluating Enriched Commercial GradeUF6, the measured concentration of236U will be used as anindicator for contamination with reprocessed uranium, on theassumption that the
35、re is no opportunity for contamination withirradiated uranium that has not been processed to remove themajority of fission products. Uranium isotopic concentrationsshall be determined and reported for234U,235U, and236U.5.5 RadionuclidesThe following values represent limitsobtainable from the enrichm
36、ent of UF6feed materials at thecorresponding limits of Specification C787. For purposes ofdetermining conformance with these limits, the observedvalues shall be rounded to the nearest significant digit indicatedin accordance with the rounding method of Practice E29. Forexample, for234U in Enriched C
37、ommercial Grade UF6theobserved value would be rounded to the nearest 0.1 3103g234U/g235U.Enriched Commercial Grade UF6Enriched Reprocessed UF6232U 0.0001 g/gU, see 5.5.1, 5.5.2, and 5.5.3 0.050 g/gU, see Note 1234U11.03 103g/g235U, see Note 2 2000 g/gU, see Note 1236U 250 g/gU, see 5.5.3 see Note 19
38、9Tc 0.01 g/gU, see 5.5.4 5 g/gU, see Note 15.5.1 If the236U measurement result is less than 125 g/gU,then measurement of232U is not required unless agreed uponbetween the buyer and seller.5.5.2 If the236U measurement result is greater than 125 butless than 250 g/gU, then measurement and reporting of
39、232Uis required for routine acceptance of the UF6.5.5.3 The buyer may consider acceptance of the lot above250 g/gU on the basis of the total significance of all themeasured levels of radionuclides to determine the suitabilityfor intended use in the fuel fabrication and irradiation. Ifthe236U measure
40、ment result is greater than 250 but less than500 g/gU, then measurement of232U and notification ofresults before shipment are required.5.5.4 The buyer and seller may agree to waive the require-ment to measure99Tc, provided that (1) the236U content is lessthan 125 g/gU; and (2) adequate capability to
41、 meet the99Tclimit for Commercial Natural UF6can be demonstrated throughquality assurance records. Such records shall include theresults of the sellers periodic measurements of99Tc in theUF6.NOTE 1Enrichment of Reprocessed UF6feed material at the limit ofSpecification C787 could be expected to reach
42、 these limits. Defining theselimits does not imply that any fuel fabrication plant designed for EnrichedCommercial Grade UF6could handle Enriched Reprocessed UF6withoutdilution with Enriched Commercial Grade UF6and other special precau-tions. With respect to the variability of Reprocessed UF6from va
43、rious fuelhistories and the demands that would be placed on the fuel fabricators andusers, it could be necessary for the seller and buyer to agree on lowerlimits after enrichment than implied by Specification C787 feed limits.NOTE 2A234U content greater than 10.0 3 103g/g235U shall requireagreement
44、in advance between the parties (for example, supplier, receiver)to accept the material. It is recognized that some applications may notallow for the limit in the table due to licensing, regulatory, or contractuallimitations.6. Sampling6.1 A representative sample of sufficient size to performtests pr
45、escribed shall be taken while the material is liquid andhomogeneous. Relevant sample procedures are given in Prac-tice C1052, USEC Report USEC-651, and DOE Report ORO-671-1.6.2 Alternatively, if the cylinder is filled in the gas phase, arepresentative sample may be taken during the transfer accord-i
46、ng to Practice C1703. It will have to be demonstrated that Gassampling is equivalent to Liquid sampling as representative ofthe bulk material in cylinder. Otherwise, the use of thisalternative technique should be agreed between buyer andseller.6.3 All samples shall be clearly identified including th
47、esellers lot number. It shall be stated whether samples havebeen taken in liquid or gas phase and whether they have beentaken during or after filling.6.4 All containers used for a lot shall be positively identifiedas containing material from a particular homogeneous lot.7. Test Methods for Chemical
48、and Isotopic Analysis7.1 Chemical and isotopic analysis shall conform to TestMethods C761, or demonstrated equivalent, as mutually agreedupon between the buyer and seller.8. Packaging, Handling, and Shipping8.1 Procedures for packaging, handling, and shipping UF6are given in ANSI N14.1, USEC Report
49、USEC-651, and DOEReport ORO-671-1 or appropriate national or internationalprocedures.8.2 Cylinders used for transport of Reprocessed UF6shallnot be used for Enriched Commercial Grade UF6unlessdecontaminated internally before filling with Enriched Com-mercial Grade UF6. Appropriate documentation shall be pro-vided as agreed between buyer and seller to confirm that acylinder has been used exclusively for enriched commercialgrade UF6or has been internally decontaminated.9. Quality Assurance9.1 Quality assurance requirements shall be agreed uponbe
